Saturday, November 7, 2015

Docker: How to setup Swarm with etcd?

Alright, let me start by sharing some information about my test environment:
(i) 3 nodes (hdp1, hdp2 and hdp3) running CentOS 7.1.1503
(ii) Docker v1.9.0
(iii) etcd 2.1.1 (running only on hdp1) listening for client connection at port 4001

Node "hdp1" will be Swarm Master.

(1) Firstly, let's reconfigure the Docker daemon running on ALL the nodes by adding "-H tcp://".

vi /usr/lib/systemd/system/docker.service
[Amend the line] ExecStart=/usr/bin/docker daemon -H fd:// -H tcp://

(2) You would have to reload systemctl and restart docker on ALL the nodes after the above changes.

systemctl daemon-reload
systemctl restart docker
[To verify] ps -ef | grep docker

(3)  Make sure "etcd" is running. If not, please start it and make sure it's listening on the intended port (4001 in this case).

systemctl start etcd
[To verify] netstat -an | grep [port] | grep LISTEN

(4) On the other nodes (non-swarm-master - in this case "hdp2" and "hdp3"), execute the following command to join them to the cluster:

docker run -d swarm join --addr=[IP of the node]:2375 etcd://[IP of etcd host]:[port]/[optional path prefix]

WHERE (in this example)
[IP of the node] = IP address of node "hdp2" and "hdp3"
[IP of etcd host] = IP address of node "hdp1" where the only etcd instance is running
[port] = Port that etcd uses to listen to incoming client connection (in this example = 4001)
[optional path prefix] = Path that etcd uses to store data about the registered Swarm nodes

The final command:
docker run -d swarm join --addr= etcd://
docker run -d swarm join --addr= etcd://

(5) You can verify that the nodes are registered with the following command:

etcdctl ls /swarm/docker/swarm/nodes

(6) If all nodes are registered successfully, you can now start up the Swarm Master (in this example, on node "hdp1").

docker run -p [host port]:2375 -d swarm manage -H tcp:// etcd://[IP of etcd host]:4001/swarm

WHERE [in this example]
[host port] = 9999 (or any other free network port you selected - you will use this port to communicate with Swarm Master)
[IP of etcd host = IP address of node "hdp1" where the only etcd instance is running


docker run -p 9999:2375 -d swarm manage -H tcp:// etcd://

(7) To verify that the Swarm cluster is now working properly, execute the following command:

docker -H [IP of the host where Swarm Master is running]:[port] info

WHERE (in this example)
[IP of the host where Swarm Master is running] = Node "hdp1" (
[port] = 9999 (refer to Step (6) above)

NOTE: You can use any Docker CLI as normal with Swarm cluster =>

docker -H [IP of the host where Swarm Master is running]:[port] ps -a
docker -H [IP of the host where Swarm Master is running]:[port] logs [container id]
docker -H [IP of the host where Swarm Master is running]:[port] inspect [container id]

(8) Let's spin up a container and see how your Swarm cluster handles it.

docker -H [IP of the host where Swarm Master is running]:[port] run -d --name nginx-1 -p 80 nginx

(9) Let's check where the container is running.

docker -H [IP of the host where Swarm Master is running]:[port] ps -a

(10) You can stop the running container by issuing:

docker -H [IP of the host where Swarm Master is running]:[port] stop [container id]

Tuesday, November 3, 2015

Mesos/Kubernetes: How to install and run Kubernetes on Mesos with your local cluster?

First of all, let me share with you my test environment:
(1) CentOS 7.1.1503 (nodes = hdp1, hdp2 and hdp3)
(2) HDP 2.3.2 (re-using the installed Zookeeper)
(3) Docker v1.8.3
(4) golang 1.4.2
(5) etcd 2.1.1

The official documentation for Kubernetes-Mesos integration can be found here. It uses Google Compute Engine (GCE), but this blog entry will share about deploying Kubernetes-Mesos integration on a local cluster.

Ok, let's begin...


(1) A working local Mesos cluster
NOTE: To build one, please refer to this.

(2) Install Docker on ALL nodes.
(a) Make sure yum has access to the official Docker repository.
(b) Execute "yum install docker-engine"
(c) Enable docker.service with "systemctl enable docker.service"
(d) Start docker.service with "systemctl start docker.service"

(3) Install "golang" on the node which you wish to install and deploy Kubernetes-Mesos integration.
(a) Execute "yum install golang"

(4) Install "etcd" on a selected node (preferably on the node that host the Kubernetes-Mesos integration for testing purposes).
(a) Execute "yum install etcd"
(b) Amend file "/usr/lib/systemd/system/etcd.service" (see below):
ExecStart=/bin/bash -c "GOMAXPROCS=$(nproc) /usr/bin/etcd"
ExecStart=/bin/bash -c "GOMAXPROCS=$(nproc) /usr/bin/etcd --listen-client-urls --advertise-client-urls http://[node_ip]:4001"
[node_ip] = IP Address of the node (hostname -i)

(c) Reload systemctl daemon with "systemctl daemon-reload".
(d) Enable etcd.service with "systemctl enable etcd.service".
(e) Start etcd.service with "systemctl start etcd.service".


Build Kubernetes-Mesos

NOTE: Execute the following on the node selected to host the Kubernetes-Mesos integration.
cd [directory to install kubernetes-mesos]
git clone
cd kubernetes


Export environment variables

(1) Export the following environment variables:

export KUBERNETES_MASTER_IP=$(hostname -i)
export MESOS_MASTER=[zk://.../mesos]
export PATH="[directory to install kubernetes-mesos]/_output/local/go/bin:$PATH"

[zk://.../mesos] = URL of the zookeeper nodes (Eg. zk://hdp1:2181,hdp2:2181,hdp3:2181/mesos)
[directory to install kubernetes-mesos] = Directory used to perform "git clone" (see "Build Kubernetes-Mesos" above).

(2) Amend .bash_profile to make the variables permanent.
(3) Remember to source the .bash_profile file after amendment (. ~/.bash_profile).


Configure and start Kubernetes-Mesos service

(1) Create a cloud config file mesos-cloud.conf in the current directory with the following contents:
$ cat <<EOF >mesos-cloud.conf
        mesos-master        = ${MESOS_MASTER}
If you have not set ${MESOS_MASTER}, it should be like (example) "zk://hdp1:2181,hdp2:2181,hdp3:2181/mesos".

(2) Create a script to start all the relevant components (API server, controller manager, and scheduler):

km apiserver \
  --address=${KUBERNETES_MASTER_IP} \
  --etcd-servers=http://${KUBERNETES_MASTER_IP}:4001 \
  --service-cluster-ip-range= \
  --port=8888 \
  --cloud-provider=mesos \
  --cloud-config=mesos-cloud.conf \
  --secure-port=0 \
  --v=1 >apiserver.log 2>&1 &

sleep 3

km controller-manager \
  --master=${KUBERNETES_MASTER_IP}:8888 \
  --cloud-provider=mesos \
  --cloud-config=./mesos-cloud.conf  \
  --v=1 >controller.log 2>&1 &

sleep 3

km scheduler \
  --address=${KUBERNETES_MASTER_IP} \
  --mesos-master=${MESOS_MASTER} \
  --etcd-servers=http://${KUBERNETES_MASTER_IP}:4001 \
  --mesos-user=root \
  --api-servers=${KUBERNETES_MASTER_IP}:8888 \
  --cluster-dns= \
  --cluster-domain=cluster.local \
  --contain-pod-resources=false \
  --v=2 >scheduler.log 2>&1 &

Since CentOS uses systemd, you will hit this issue. Hence, you need to add the "--contain-pod-resources=false" to the scheduler (in bold above).

(3) Give execute permission to the script (chmod 700 <script>).
(4) Execute the script.


Validate Kubernetes-Mesos services
$ kubectl get pods
# NOTE: Your service IPs will likely differ
$ kubectl get services
NAME             LABELS                                    SELECTOR   IP(S)          PORT(S)
k8sm-scheduler   component=scheduler,provider=k8sm         <none>   10251/TCP
kubernetes       component=apiserver,provider=kubernetes   <none>     443/TCP
(4) Lastly, look for Kubernetes in the Mesos web GUI by pointing your browser to http://[mesos-master-ip:port]. Go to the Frameworks tab, and look for an active framework named "Kubernetes".

Kubernetest framework is registered with Mesos

Let's spin up a pod

(1) Write a JSON pod description to a local file:
$ cat <<EOPOD >nginx.yaml
apiVersion: v1
kind: Pod
  name: nginx
  - name: nginx
    image: nginx
    - containerPort: 80
(2) Send the pod description to Kubernetes using the "kubectl" CLI:
$ kubectl create -f ./nginx.yaml
Submitted pod through kubectl
(3) Wait a minute or two while Docker downloads the image layers from the internet. We can use the kubectl interface to monitor the status of our pod:
$ kubectl get pods
nginx     1/1       Running   0          14s
(4) Verify that the pod task is running in the Mesos web GUI. Click on the Kubernetes framework. The next screen should show the running Mesos task that started the Kubernetes pod.
Mesos WebGUI shows active Kubernetes task

Mesos WebGUI shows that the Kubernetes task is RUNNING
Click through "Sandbox" link of the task to get to the "executor.log"

An example of "executor.log"

Connected to the node where the container is running

Getting Kubernetes to work on Mesos can be rather challenging at this point of time.

However, it is possible and hopefully, over time, Kubernetes-Mesos integration can work seamlessly.

Have fun!

Saturday, October 10, 2015

Docker: All Containers Get Automatically Updated /etc/hosts (!?!?!?)

While I have always wanted such feature (automatically updated /etc/hosts for all running containers), I understand that Docker does not provide it natively (just yet - or at least AFAIK). I also understand some security issues that might come with such feature (not all running containers want other containers to connect to it).

Anyway, about 2 weeks ago, while I was dockerizing a system automation application that requires at least 2 running nodes (containers), I found that the feature was silently available*.

* I went through the Release Notes of almost all recent releases and could not find such feature being mentioned. If I got it wrong, please point me to the proper Release Notes. Thanks!

Before I forget, let me share with you the reason I have always wanted such feature. My reason is simple - I need all my running containers to know the "existence" of other related containers and have a way to communicate with them (in this case, through /etc/hosts).

My test environment was on CentOS 7.1 and Docker 1.8.2.

(1) Firstly, I started a container without any hostname and container name. You can see that the /etc/hosts file was updated with:
(a) the container ID as the hostname
(b) the container name as the hostname

(2) Next, I started another container with an assigned hostname of "node1". You can see that now the /etc/hosts was updated with:
(a) the assigned hostname
(b) the container name as the hostname

(3) To spice it up a little bit more, I started another container with an assigned hostname and gave the container a name. You can see that the /etc/hosts was updated with:
(a) the assigned hostname
(b) the given container name

(4) The next test was to start up 3 containers with different hostname and given name and left all of them running. You can see that "node1" was started and its /etc/hosts was updated accordingly.

(5) Next, I started "node2" and its /etc/hosts was updated with details of "node1" too.

(6) What happened to the /etc/hosts of "node1" at this moment? Surprise, can see that its /etc/hosts was updated with details of "node2" too.

(7) Just to make sure it's not devaju. I started the third container ("node1" and "node2" were still running). This time I wasn't surprised to see that the /etc/hosts of "node3" was updated with details of "node1" and "node2".

(8) Lastly, let's check the /etc/hosts of "node1" and "node2". Viola, they are updated too!

Seriously, I am not sure whether this feature has been available for some time or it is an experimental feature. Anyway, I like it...for the thing I do! So, I am not speaking for you :)

Sunday, October 4, 2015

Docker: Sharing Kernel Module

This is more like a request-for-help entry :)

I was working on a small project to dockerize a system automation application that supports clustering. Everything was working fine until the very last minute - during system startup!!!

The database was working fine in a primary-standby setup. The system automation application was running fine on both of the nodes in the cluster. Configuration went fine too.

However, when I started the automation monitoring, KABOOOOMMM, problem happened!

What happened was that the first node came up fine, but the second node seems to be reporting weird status. A quick read of the log file told me that the second node was unable to load the "softdog" kernel module and would not be able to initialize. The reason is very likely because the first node has already gotten hold of the kernel module.

Ok, I have to admit that this is a silly mistake I made and an oversight before I started the project.

Anyway, I would like to share what I learned from this experience:
(1) It is possible to have access to kernel module by:
(a) mounting the /lib/modules directory read-only into the container (-v /lib/modules:/lib/modules:ro).
(b) the kernel version of the host machine must be the same with the kernel version of the image/container.
(c) run the container with --privileged option.

For those people out there that are trying to dockerize applications that require kernel module, please be reminded that all containers on a same host would share the same underlying (host) kernel. Hence, you have to make sure that the application would still work under such condition.

I am not a kernel expert and have not ventured into this area in Docker previously, so any help is appreciated - SOS!!!!!

Saturday, September 12, 2015

Running Apache Spark on Mesos

Running Apache Spark on Mesos is easier than I thought!

I have 3 nodes at home (hdp1, hdp2 and hdp3) which are running Hortonworks Data Platform (HDP). I have HDFS, Zookeeper and Spark installed on the cluster.

To test running Spark on Mesos, I decided to reuse the cluster for simplicity's sake.

All I did was:
(1) install Mesos master on node hdp1.
(2) install Mesos slave on node hdp2 and hdp3.
(3) configure the master and slaves accordingly.

(i) For more information about the installation and configuration of Mesos, you can refer to this blog entry.
(ii) I reuse Zookeeper that was installed with HDP.

Once Mesos is up and running, I decided to carry out a very simple test that is described as follow:
(1) Use "spark-shell" as the Spark client to connect to the Mesos cluster.
(2) Load a sample text file into HDFS.
(3) Use spark-shell to perform a line count on the loaded text file.

First, let's see what is the command that you can use to connect spark-shell to a running Mesos cluster.

TIPS: All you need to do is to use the "--master" option to point to the Mesos cluster at "mesos://<IP-or-hostname of Mesos master>:5050".

Then, let's load a sample text file into HDSF using the "hadoop fs -put" command.

Once the sample text file is loaded, let's create a spark RDD using it.

TIPS: You can use the "sc.textFile" function and points it to "hdfs://<namenode>:8020/<path to file>".

After the RDD is created, let's run a count on it using the "count()" function.

You can see from the screenshot above and below that, Spark (through Mesos) has submitted 2 tasks that are executed on node hdp2 and hdp3 respectively.

You can also see from the screenshot above that the end result is returned as "4" (which means 4 lines in the file - which is correct!).

So, that is how easy it is to run Spark on Mesos.

Hope that you are going to try it out!

Saturday, September 5, 2015

Neo4j: How to import data using neo4j-import?

One of the few first things to do while learning a new database is to load some sample data and there is no difference when it comes to Neo4j.

With Neo4j, my preferred way of data loading is through the neo4j-import command.

While the documentation available is decent, new users might face some challenges accomplishing it (at least I was struggling at one point of time :).

That is the purpose of me writing this blog entry - to help those that need a quick-start guide for loading data into Neo4j.

Let's do it in a cookbook manner...

(1) Read the following documentations:

It's ok if you do not understand fully. Please allow me to share with you an example.

(2) Let's create the CSV needed to represent NODE and RELATIONSHIP.

The example that I have here is a simple banking system that contains the following NODEs:
(c) ATM

and the following RELATIONSHIPs:

(3) First, let's create the CSV files for the NODEs.

According to the documentation (see excerpt below), the CSV header for a NODE must contain an ID and a LABEL.


The following field types do additionally apply to node data sources:
Each node must have a unique id which is used during the import. The ids are used to find the correct nodes when creating relationships. Note that the id has to be unique across all nodes in the import, even nodes with different labels.
Read one or more labels from this field. For multiple labels, the values are separated by the array delimiter.

How do we do that? Simple...

[danielyeap@myhost neo4j-data]$ cat customer.csv 
[danielyeap@myhost neo4j-data]$ cat atm.csv 
1,Damansara Uptown,ATM
2,Kota Damansara,ATM
3,Jalan Ipoh,ATM
[danielyeap@myhost neo4j-data]$ cat account.csv 

(4) Since the NODEs are taken care of, let's craft our RELATIONSHIP CSV files.


For relationship data sources, there’s three mandatory fields:
The relationship type to use for the relationship.
The id of the start node of the relationship to create.
The id of the end node of the relationship to create.

[danielyeap@myhost neo4j-data]$ cat rel-cust-acct.csv 
[danielyeap@myhost neo4j-data]$ cat rel-txfer.csv 
[danielyeap@myhost neo4j-data]$ cat rel-withdraw.csv 

(5) Now that we have all the files that we need to perform the data loading, it is time to execute the command:

[danielyeap@myhost neo4j-data]$ neo4j-import --into ~danielyeap/neo4j/data/graph.db --nodes customer.csv --nodes account.csv --nodes atm.csv --relationships rel-txfer.csv --relationships rel-cust-acct.csv --relationships rel-withdraw.csv 

Importing the contents of these files into /home/danielyeap/neo4j/data/graph.db:





Available memory:
  Free machine memory: 11.08 GB
  Max heap memory : 2.73 GB

[*>:??------------------------------------------------------------------------------||NODE:7.||] 10k
Done in 481ms
Prepare node index
[*DETECT:7.63 MB-------------------------------------------------------------------------------]   0
Done in 11ms
Calculate dense nodes
[*>:??-----------------------------------------------------------------------------------------]   0
Done in 297ms
[*>:??--------------------------------------------------------------------------------------|P|] 10k
Done in 68ms
Node --> Relationship
[*>:??-----------------------------------------------------------------------------------------] 10k
Done in 10ms
Relationship --> Relationship
[*>:??-----------------------------------------------|v:??-------------------------------------] 10k
Done in 10ms
Node counts
[*COUNT:76.29 MB-------------------------------------------------------------------------------] 10k
Done in 218ms
Relationship counts
[*>:??------------------------------------------|COUNT-----------------------------------------] 10k
Done in 10ms

IMPORT DONE in 2s 664ms. Imported:
  13 nodes
  22 relationships
  66 properties


(i) You can refer to the documentation about the command line HERE.
(ii) The "--into" option must point to the directory where neo4j database is located (look in <neo4j_install_dir/conf/ =>


(iii) If there is an error about existing database, you can use the following procedure to remove it:
~ While Neo4j is up and running, go to "org.neo4j.server.database.location" and run "rm -rf *".
~ After all the files under that directory are removed, execute the "neo4j-import" command again.
~ After the import is successful, restart Neo4j (command = neo4j restart). 
~ Login to Neo4j web interface and you should see your data loaded.

Saturday, August 22, 2015

D3.js: How to draw a Node Relationship Graph like Neo4J?

First of all, I am deeply sorry for the lack of update for this blog! I have been really busy with my work, family and self-learning.

Anyway, this entry is about some cool technologies that I have been spending time lately - Neo4j and D3.js.

I have always been curious about graph database. Recently, I have finally conceded to my better curious half and started to get my hands on Neo4j (one of the more popular graph database engine).

I am greatly impressed by its Web GUI that is able to draw a proper Node -> Relationship graph that is both pretty and practical.

Courtesy from Neo4j website

At work, I have a sudden need for such a graph to analyze some really complex text-based source-target relationships. That was how D3.js came into play!

I have always known that I need to lay my hands on D3.js one day for data visualisation. This need at work just justified it.

After some googling and reading, I ended up with the codes below:
NOTE: Simplified to increase readability!

<!DOCTYPE html>
<html lang="en">
<%@page pageEncoding="UTF-8" contentType="text/html; charset=UTF-8"%>
<title>Node Relationship Graph</title>
<script type="text/javascript" src="d3/d3.min.js"></script>
<style> {
  fill: none;
  stroke: #666;
  stroke-width: 1.5px;

circle {
  fill: #ccc;
  stroke: #fff;
  stroke-width: 1.5px;

text {
  fill: #000;
  font: 10px sans-serif;
  pointer-events: none;


<script type="text/javascript">
d3.csv("data/lsrel.csv", function(error, links) {

var nodes = {};
var rel = {};

// Compute the distinct nodes from the links.
links.forEach(function(link) { = "rel" + link.relnum; 
    // link.relnum = link.relnum;
   var sLinkSrc = link.source;
   var sLinkTgt =;
    link.source = nodes[link.source] || 
        (nodes[link.source] = {name: link.source, relcnt: 0, srccnt: 0, tgtcnt: 0}); = nodes[] || 
        (nodes[] = {name:, relcnt: 0, srccnt: 0, tgtcnt: 0});
    link.relationship = link.relationship;
   if (nodes[sLinkSrc])
         nodes[sLinkSrc]["relcnt"] = nodes[sLinkSrc]["relcnt"]+1;
         nodes[sLinkSrc]["srccnt"] = nodes[sLinkSrc]["srccnt"]+1;

   if (nodes[sLinkTgt])
         nodes[sLinkTgt]["relcnt"] = nodes[sLinkTgt]["relcnt"]+1;
         nodes[sLinkTgt]["tgtcnt"] = nodes[sLinkTgt]["tgtcnt"]+1;

   // console.log(JSON.stringify(nodes));
   // console.log("NODEPROP: " + nodes[sLinkSrc].name);


var width = screen.width-80,
    height = screen.height-80;

console.log("Width: " + width);
console.log("Height: " + height);

var force = d3.layout.force()
    .size([width, height])
    .on("tick", tick)

var drag = force.drag()
            .on("dragstart", dragstart);

var svg ="body").append("svg")
    .attr("width", width)
    .attr("height", height);

// build the arrow.
    .attr("id", String)
    .attr("viewBox", "0 -5 10 10")
    .attr("refX", 22)
    .attr("refY", -1)
    .attr("markerWidth", 8)
    .attr("markerHeight", 8)
    .attr("orient", "auto")
    .attr("d", "M0,-5L10,0L0,5");

// add the links and the arrows
var path = svg.append("svg:g").selectAll("path")
   .attr("id", function(d) { return; } )
    .attr("class", "link")
    .attr("marker-end", "url(#end)");

var mytext = svg.append("svg:g").selectAll("text")
.attr("dx", "150")
.attr("dy", "-8")
 .attr("xlink:href", function(d) { return "#" +; })
 .attr("style", "fill:magenta; font-weight:bold; font-size:12")
 .text(function(d) { return d.relationship; } );

// define the nodes
var node = svg.selectAll(".node")
    .attr("class", "node")

// add the nodes
    .attr("r", 12)
    .attr("fill", "grey")
   .text(function(d) { return "Source: " + d.srccnt + " ~ Target: " + d.tgtcnt; });

// add the text
    .attr("x", 12)
    .attr("dy", ".35em")
    .attr("style", "fill:blue; font-weight:bold; font-size:16")
    .text(function(d) { return; });

   .attr("text-anchor", "middle")
    // .attr("style", "font-weight:bold; font-size:12")
    .attr("style", function(d) {
      if (d.relcnt >= 3)
         return "font-weight:bold; font-size:12; fill:red"
         return "font-weight:bold; font-size:12"
   .text(function(d) { return d.relcnt; });

// add the curvy lines
function tick() {
    path.attr("d", function(d) {
        var dx = - d.source.x,
            dy = - d.source.y,
            dr = Math.sqrt(dx * dx + dy * dy);
        return "M" +
            d.source.x + "," +
            d.source.y + "A" +
            dr + "," + dr + " 0 0,1 " +
   + "," +

         .attr("transform", function(d) {
             return "translate(" + d.x + "," + d.y + ")"; });

function dragstart(d)
{"fixed", d.fixed = true);
if (error)



A sample of the input file "lsrel.csv" is as follow:


The output of the D3.js script based on the data above:

Hope you guys like it!

Saturday, April 18, 2015

Docker: OpenDayLight (ODL)

I have always wanted to learn more about Software Defined Network (SDN) when I first heard about it from a colleague (now ex-colleague) about 2 years ago.

However, I have been really busy (a.k.a lazy) with work and family. Not until recently when I stumbled upon an interesting opportunity that drove me to take a peek at it.

Ok, the first big question is "OpenFlow or OpenDayLight"? Since I do not have a lot of time to perform research on their respective strengths and weaknesses, I have resorted to a very "scientific" way to choose among the two. In the end, I chose OpenDayLight because (wait for it...) I prefer their website :).

Since I am a big fan of Docker, it doesn't make sense for me to not install OpenDayLight on Docker. A quick google landed me with this. I am not interested in Debian, so I made some changes to the Dockerfile to switch the base image to Centos 6.6.

FROM centos:6.6

# Install required software (170MB)
RUN yum update -y && yum install -y tar wget java-1.7.0-openjdk

# Download and install ODL
RUN mkdir opendaylight

RUN wget -q "" && \
    tar -xf distribution-karaf-0.2.3-Helium-SR3.tar.gz -C opendaylight --strip-components=1 && \
    rm -rf distribution-karaf-0.2.3-Helium-SR3.tar.gz

EXPOSE 162 179 1088 1790 1830 2400 2550 2551 2552 4189 4342 5005 5666 6633 6640 6653 7800 8000 8080 8101 8181 8383 12001

WORKDIR /opt/opendaylight
ENV JAVA_HOME /usr/lib/jvm/jre-1.7.0-openjdk.x86_64
CMD ["./bin/karaf", "server"]

(i) My test shows that Java 8 is currently not supported and will give weird Java NullPointerException while executing command.
(ii) You can download the Dockerfile here.

By executing "docker build -t opendaylight:helium ." in the directory where the Dockerfile is stored, I ended up with a Docker image that contains OpenDayLight.

OpenDayLight on Docker

After starting the container using "docker run" command (refer to the above screenshot), it is time to SSH connect to it and install some ODL components.

This can be achieved by using the Karaf client (download).

Connect to the ODL container through Karaf client
To list all supported features, you can execute the "feature:list" command.

List all supported features
To list currently installed features, you can use the "feature:list -i" command.

Default installed features
To install some basic features, you can execute "feature:install odl-restconf odl-l2switch-switch odl-mdsal-apidocs odl-dlux-core".

Install some basic features
Now, you can proceed to login to OpenDayLight User Experience (DLUX) using URL "<IP of the Docker container>:8181/dlux/index.html.
The default user ID and password are "admin" and "admin" respectively.

DLUX login page
Voila, you are in!

DLUX login page
To learn ODL further, you can download its documentation from this page.

I am still far from really knowing how to use ODL properly. I might even explore OpenFlow one day.

Anyway, I had fun trying it out and hope that you would too!

Sunday, April 12, 2015

Java: Stream Control Transmission Protocol (SCTP)

If you have not heard about SCTP, don't fret! Me neither, until recently.

For a good explanation about SCTP, you can read this and this and this. In short, SCTP is basically TCP on steroids!

People who knows me well knew that I am always curious about new technology or technology new to me (sorry if I confuse you :).

How can I miss the chance to explore SCTP futher? Of course, the language of choice would be Java - still my favorite language after all these years.

First, I created the SctpServer class to serve as a SCTP server.
Next, I created the SctpClient class to serve as the SCTP client that will connect to multiple SCTP servers started on different ports (same host in this case) through a single socket (YES, you read it right, single socket!).

Two SctpServers listening on port 12000 and 12001. An SCTP client sends message to them on the same socket.
From the image above, you can see that there are 2 SctpServer listening on port 12000 and 12001 respectively.

Once the ScptClient connects to them and send them messages, you can see both servers reported that the connection came from port 43975 with stream number of 0 (SctpServer that listens on port 12000) and 1 (SctpServer that listens on port 12001) respectively.

SctpClient uses SctpMultiChannel for its communication.

Now, if you take a look at the codes for SctpClient, there is no "connect" statement at all. That is because a new association will automatically be created for every "send" command. [reference]

The destination of your message/data is now encapsulated in the MessageInfo object.

If you have the interest to explore SCTP further, you can download the sample codes here.

Enjoy hacking!

Wednesday, April 8, 2015

Docker User Group Malaysia

I created the Docker User Group Malaysia on Facebook a few months ago.

The intention is to share information and knowledge with all Docker users within Malaysia.

From 2 members (myself and a colleague of mine), it has now grown to 8 members (some nice folks from Mindvalley).

If you are interested to join or learn more about Docker, you can visit this Facebook group anytime!

Monday, April 6, 2015

Apache Storm: HBase Bolt

Starting with version 0.9.2-incubating, Storm included support for HBase as bolt. You no longer need to seek third party packages to do that, which is a great news!

To refer to the APIs and documentation, you can go here.

I have coded a simple Storm application that takes Kafka as spout and HBase as bolt. In other words, the application will get its data from Kafka and then write to HBase.

One interesting item within Apache Storm is stream grouping (how tuples produced by spouts will be handled by available bolts). To read more about stream grouping, you can refer here.

Lastly, if you want to try it out yourself, you can download the sample codes here.

Storm UI that shows Kafka spout and HBase bolt processing

Tuesday, March 10, 2015

Apache Storm: How to add external JARs or packages into CLASSPATH while running 'storm jar'?

I have been playing with 'storm-kafka' and 'storm-hbase' lately. Basically, they are projects/tools that one can use to integrate Kafka and HBase with storm.

My project was to have Kafka as spout and HBase as bolt. In other words, my application will pull data from Kafka and then write the output to HBase. In other other words (pun intended :), I need to have the storm-kafka and storm-hbase JAR included when I run my Storm topology.

There are a few ways to do this:
(1) Put the JARs under STORM_BASE_DIR
(2) Put the JARs under STORM_BASE_DIR/lib
(3) Put the package under STORM_CONF_DIR
(4) Include the package into the topology JAR

After trying the above few methods, my favourite is method #4. However, it is not without its own pain points.

Let me explain why I do not like the other methods.

Method #1
By putting JARs into STORM_BASE_DIR, I have a feeling that I have 'corrupted' the directory. Messing up a standard directory of a product is not my cup of tea.

Method #2
See Method #1 above.

Method #3
Since the codes do not search the directory declared as STORM_CONF_DIR (or USER_CONF_DIR) for JARs, you would have to put the package files in that directory. How many times have I said 'messy'? :)

Now, let's discuss Method #4. I say it is my favourite, but I never say it is the best. That is because it will grow your JAR file size greatly if you have some really big external JARs to include (beside your topology). However, I feel that it is the most acceptable approach because it is more manageable than the other methods (at least to me :).

Hence, if you are looking into including or adding external JARs while running your Storm topology, I would suggest you to include those JARs into your topology JAR for the time being until there is a neater way to do this!

Environment = HDP 2.2 (Storm 0.9.3)

Source codes of and how CLASSPATH is determined

Tuesday, March 3, 2015

Apache Mesos: Mesos + Marathon + Docker = ?

In my previous post, I talked about merging resources from multiple nodes into one using Apache Mesos.

I also talked about the 2 reasons I decided to pick up Mesos:
(1) Google Kubernetes
(2) Docker

In this post, I am going to share the method you can use to deploy Docker container on a Mesos cluster.

* Mesos and Zookeeper have to be up and running. For installation instruction, please refer to my previous post.
** I used CentOS 6.6 as the platform. So, some commands might differ on other platforms.
*** Make sure "docker-io" "(the Docker package) is installed and the daemon is running on all Mesos slave nodes.

(1) Check and update (if needed) the /etc/mesos/zk file on the node you wish to install Marathon.

vi /etc/mesos/zk

** Make sure the IP address of the Zookeeper server is written there

(2) Install Marathon (using the Mesosphere repository created in the previous post) on the node selected above (Master node is recommended for testing purpose and ease of maintenance):

yum install marathon

(3) Make sure Marathon is up and running after the installation. Otherwise, start it using:

initctl start marathon 

** Use "ps -ef" command to verify the Marathon process is running with the proper IP addresses (instead of 'localhost') of the zookeeper-server and Master node. If it is not, check the /etc/mesos/zk file again and restart.

(4) Update all the Mesos slave nodes with the following:

echo 'docker,mesos' > /etc/mesos-slave/containerizers

echo '5 mins' > /etc/mesos-slave/executor_registration_timeout

(5) Restart all the Mesos slave nodes:

initctl restart mesos-slave 

(6) By now, you should be ready to deploy Docker container on the Mesos cluster. To do so, you have to create a JSON file for the Docker container you wish to deploy:


   "container": {
      "type": "DOCKER",
      "docker": {
         "image": "",
         "network": "HOST"
   "id": "centos63",
   "instances": 1,
   "cpus": 4,
   "mem": 2048,
   "uris": [],
   "cmd": "/usr/sbin/httpd -DFOREGROUND"


There are a few things to take note:
(a) For the "image" parameter, you would need to specify an image that is reachable by all of the Mesos slaves, because you would not know for sure which slave or slaves the Master will select to run the container.

** If you are using your own insecured private registry, please make sure you edit the docker "default" file (eg. /etc/sysconfig/docker or /etc/default/docker) to declare the registry as insecured and restart the Docker service (service docker restart):


(b) AFAIK, Mesos (0.21.1) only support 2 network modes now - HOST or BRIDGE. 

(c) The "cmd" parameter works like CMD in Docker.

(7) Once the JSON file is ready, you can submit to Marathon using the POST method:

curl -X POST -H "Content-Type: application/json" http://<marathon host>:8080/v2/apps -d@<JSON filename> 

Marathon GUI: After the CURL command and when Mesos is deploying the container

Marathon GUI: The container is successfully deployed and RUNNING

Mesos GUI: Shows one active task running on "mesos4" slave node

Mesos GUI: Clicking on the task shows the details (it's a SANDBOX)

Mesos GUI: STDOUT and STDERR are streamed from the container to the sandbox

On 'mesos4' node, the image is downloaded from the private repo and a container is running

On 'mesos4' node, 'docker inspect <container id>' shows the networking mode is HOST as configured

On 'mesos3' node, a HTTP connection shows HTTPD container is indeed running on 'mesos4' node